In an enterprise, a form is used in various business fields. For example, in a financial institute, a plurality of forms is prepared and the desired service of a customer is provided on the information written in a form by the customer. When a center collectively performs such a process for providing the service, the form is digitized and transferred to the center.
In the digitalization of a form, usually the contents entered into the form are recognized (character recognition). A form recognition apparatus recognizes the contents entered into a form by reading its digitalized image using an image reading device. It is common that the form transferred to the center, that is, the recognition result by the form recognition apparatus can be corrected by an operator, if necessary.
In a form, information (character strings) is arranged in an arbitrary table structure. Therefore, as a method for recognizing a character string to be recognized in a form image, there is a method for registering the layout structure of a form to be recognized. According to this method, a region where a character string to be recognized exists in a read form image can be immediately specified using the registered layout structure. A layout structure corresponding to a read form image can be also automatically extracted from a registered layout structure (Japanese Laid-open Patent Publication No. 2004-164674). The features of a layout structure can be also automatically extracted from a form image and the layout structure can be also automatically registered (Japanese Patent No. 3088019).
Usually, the number of types of forms handled in an enterprise and the like is not one. Generally, many types exist. The design (layout) of a form is also often modified for some reason. In a financial institute, a customer does not always use a prepared form. Specifically, a customer sometimes requests a service using its own form. For this reason, there is a form recognition apparatus capable of recognizing a form, that is, recognizing content mentioned on the form without registering the layout structure of a specific form in conventional form recognition apparatuses (Japanese Laid-open Patent Publication No. H9-274634 (hereinafter called “Patent document 1”), Japanese Laid-open Patent Publication No. H10-116314 (hereinafter called “Patent document 2”) and Japanese Laid-open Patent Publication No. 2006-134106 (hereinafter called “Patent document 3”). However, any conventional form recognition apparatus described in respective Patent documents 1 through 3 has low versatility and is not practical as follows.
In the conventional form recognition apparatus described in Patent document 1, a field name to be read a form and information for recognizing the content of the field name are prepared and the content of each field are recognized. However, in some form, a plurality of field names is assigned to one piece of data (description). Alternatively, in some form, a plurality of the same field names is entered for a plurality of pieces of different usage. Therefore, the types of a form that can be recognized are limited.
In the conventional form recognition apparatus described in Patent document 2, presuming that all field names are arranged in one frame, characters are recognized by to distinct a frame having predetermined regularity and other frames as an field frame and data frames, respectively. However, in some form, a character string indicating a field name is not arranged within a frame. Alternatively, in some form, a plurality of types of character strings is arranged in one frame. The latter case corresponds to, for example, a form in which a customer describes data within a frame where a printed field name is arranged.
In the conventional form recognition apparatus described in Patent document 3, for each type of a form, field names mentioned on the form are grouped, a group to which the field name existing in a read form belongs is extracted and a form type (logical structure) candidate is estimated from the extracted group. However, since one or more field names belong to each group, each group has a small amount of information. This is because the information of each group is related to all field names belonging to the group. For this reason, the type of a form can be recognized only at a level where it can be only determined which it is, an order sheet or an entry application form.
In the conventional form recognition apparatus described in Patent document 3, by collating the data type of each field name with a data type indicated by schema information corresponding to the group to which the field name belongs, it is checked whether they coincide with each other and the check result is used to recognize the type of the form. However, the check can be actually used only to specify description (data) corresponding to the field name. This is because there is usually a relationship which is established by very high possibility, between a field name and a data type of the field name. More specifically, this is because in an field name that can be grouped into one, such as  (An amount or an amount of money. A reading in Japanese is “kin”),  (A unit price. A reading in Japanese is “tanka”) and  (A payment amount of money. A reading in Japanese is “noufukingaku”), any piece of data is usually expressed numerically.
In a form, there is often a plurality of pieces of data that may correspond to a field name. Therefore, usually it is necessary to specify a correspondence relationship between a field name and data. Since a data type often varies depending on a field name, a data type can be used as information for specifying data corresponding to a field name (Patent document 1). Naturally, the above-described collation can be conducted only after specifying the corresponding relationship. Therefore, if the collation can be conducted, it is necessary that a region mentioned on data corresponding to a field name for each field name can be specified in advance. Alternatively, it is necessary that a form has such a simple design that there is no need to specify it. For this reason, it is understood that the type of a form can be recognized only at a very low level.
As other technical reference literatures, there are Japanese Laid-open Patent Publication No. H11-110479, Japanese Laid-open Patent Publication No. 2000-339406, Japanese Laid-open Patent Publication No. 2004-334913 and Japanese Patent No. 3465667.